Transformer.



G. STERN.

TRANSFORMER.

APPLICATION FILED AUG.22, 1913.

1,1 14,548. Patented Oct. 20, 1914.

Witnesses Inventor a %,,j, 7,44 George Stern w by M H is o ttorn e5 UNITED STATES PATENT OFFICE.

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TRANSFORIEI.

Specification of Letters Intent.

Patented Oct. 20, 1914.

To all whom it may concern: I

Be it known that I, Gnome STERN, a subject of the King of Prussia, residing at Berlin, Germany, have invented certain new and useful Improvements in Transformers, of which the followin is a specification.

My invention re ates particularly to 011- cooled transformers, but in its broadest aspects relates to all oil submerged electrical windings wherein it is desirable to change certain of the connections after installation. With transformers particularly it is often desirable to change certain connections, as for varying the ratio of transformation, and to do this it has been common practice to provide taps to the windings, the interconnections of which may be changed. Good practice dictates that the interconnections be made below the surface of oil and it has therefore been common to assemble the connectors at the ends of the various taps on some support or terminal board directly above the transformer and under the surface of the oil in the transformer tank, interconnecting these connectors by links. To change the connections, therefore, it is necessarv to either work under the oil, or to Withdraw sufiicient oil to lower its surface below that of the terminal board. Both methods are subject to obvious objections. To escape these objections it has been suggested that the taps be brought out through the tank and the connections changed outside. This is subject to numerous objections also, among which may be mentioned that of requiring apparatus outside of the transformer tank. Further, as the higher potentials are reached, it becomes difficult to obtain proper spacing of the taps and the terminals when they pass through the cover, and the insulated leads required for these taps and terminals very materially increase the cost.

The object of my invention is to continue the more usual and satisfactory practice of submerging the connectors in the oil of the transformer tank, and to provide means for changing the connections easily and quickly without lowering the level of the oil in the tank and without employing devices requiring any considerable manipulation beneath the surface of the oil. I do this by grouping the terminals of the taps employed in making the respective connections in differout parts of the case, and making the required connections with the tap terminals by a rod carrying an engaging means 111' sorted into the tank through a hole in, the f cover, through which the desired group of terminals is accessible. The rod and each grou of terminals it may engage partake of t nature of a common plug switch. Often the question of spacing at the tank walls will not be involved at all since it be comes unnecessary to carry leads from the taps therethroug'h, and the difliculty of working below t e oil is substantially gvercome. To change from one set of connections to another it is only necessary to pull out the rod from engagement with one group of taps and to insert it into engagement with another.

The single figure of the drawing shows diagrammatically three polyphase windings located 'on a single core within a tank with means involvi necting the win ings and changing the numbers of active turns.

The tank 1 which ma be of the usual construction, is provide with a cover 2. Through this cover project the usual insulator leads 3 carrying the terminals from the windings. The windings 4, 5 and 6 I have conventionally illustrated as assembled on the core 7. On the top of this core 7 is placed the terminal board 8. I have provided means for making three changes in the number of active turns in each of the windings, the number of turns in the windings remaining always equal to each other andY the wlndlngs a ways being connected in Taps 4, 5 and 6 are connected to similar points on-the windings 4, 5 and 6 respectively. Likewise, the taps 4 5 and 6* and 4, 5 and 6 are connected to similar points respectively, on the various windings. Connectors or terminals 9, 10 and 11 are provided for the taps 4, 5 and 6, 4", 5 and 6", and 4, 5 and 6 respectively. These connectors are assembled on the terminal board 8, all the groups being assembled in the same relative manner, but at different points on the terminal board 8. Above each group is provided an opening 12, 13 and 14 in the tank cover. To the rod 15 is attached the connector 16. The shape of the connector 16 is such that it can engage and connect tomy invention for Y-con' gether the connectors of any one of the groups of taps. The dash line 17 may indicate the normal mean oil level.

The operation is as follows: Suppose that it is desired to have the greatest number of turns of the respective windings active and connected in Y,the rod 15 is inserted through the opening 14; in the cover as shown, and the connecting means 16 is forced into engagement with the connectors 11. It will be seen that the taps 4, 5 and 6 are now connected together and hence that the windings 4, 5 and 6 are connected in Y and that all of the turns of the respective windings are active. If it is desired to cut out some of these turns, the rod 15 may be removed from the opening 14, the cover removed from the opening 13, the rod 15 inserted therein and the connecting means 16- forced into engagement with the group of connectors 10. After this operation the windings are again connected in Y, but now a smaller portion of each winding is active and the windings are connected through the taps 4 5 and 6 In a similar way the Y- connection may be changed to taps 4, 5 and 6 by employing the connectors 9. It will be apparent from this that, although the terminal board 8 with the connectors 9, 10 and 11 is a considerable distance below the surface of the oil, the changes in the connections may be readily and quickly made and that it is not necessary that any considerable work be done below the surface of the oil, or that the surface of the oil be lowered at all.

It will be understood that in may be employed in considerab y modified constructions.

What I claim as new and desire to secure by Letters Patent of the United States, is,-

The combination with a fluid containing tank, a fluid contained therein and electrical windings submerged in said fluid, of a plurality of groups of taps connected to said windings, terminals attached to said taps and submerged in said fluid, the terminals attached to one group of taps being accessible through an opening in the tank, the terminals attached to another group of taps being similarly located relatively to each other as the terminals of the first mentioned group of taps, and also being accessible through an opening in said tank, and a member adapted to be inserted into the tank through the proper opening, the member and each group of terminals partaking of the nature of a plug switch, the member being provided with means for connecting together the terminals of any one of said groups.

In witness whereof, I have hereunto set my hand this 6th day of August, 1913.

GEORGE STERN.

Witnesses HENRY HAsPER, ARTHUR SGHROEDER.

invention 

